When should I replace my CFL bulbs with LEDs?

When should you replace your bulbs: as they break or as soon as possible?
14 March 2017


Traditional incandescent lightbulb



My home in Cambridge has about 60% compact fluorescent lightbulbs and the rest are LEDs. Should I be chucking out the former even though they still work on the grounds that they use lots of power compared with LEDs or should I just wait until they break over time and only replace them with LEDs then?


Ricky Navthani took Philip's question to Andy Smale from the consultancy Energy Expert:

Andy - LED technology is now far superior to compact fluorescent designs.  LED bulbs switch on instantly at full brightness, rather than taking a minute or two to warm up, and most LED bulbs now replicate the yellowish light of old filament bulbs very closely, whereas CFL bulbs can still sometimes have a slight pink or purple tinge. On the downside, a minority of LED bulbs have a high frequency flicker which bothers some people more than others.

Ricky - It looks like there’s not much competition between LEDs and CFLs. But would buying LED bulbs cost me more money than they’re worth?

Andy - The best LED bulbs use about half the energy of CFL bulbs for the same light output and are now claimed to last between 10 and 25 years with typical use. If you buy a pack of them, you can get them for about £2 each, so they will pay for themselves in savings over just 2.5 years if you are replacing a CFL, and within 4 months when replacing a filament bulb.

Ricky - OK, in just a few years the amount they’ll save me in energy costs more than makes up for it! But can I justify it on environmental grounds? What about the overall CO2 emissions?

Andy - Likewise, the carbon emissions resulting from manufacturing a new LED bulb are about 4kg of CO2 and recycling your old CFL bulb releases about 100g of CO2 or in the region of about 3kg if you drive 3 miles or so to your nearest recycling centre and back. So there’s a one off 7-8 kg CO2 cost in replacing the bulbs. But since LEDs release about 2 kg less CO2 a year, assuming average usage, in 4 years you’ll also have released less CO2 overall than if you hadn’t switched them at all. That saving is compounded if you replace all the bulbs in one go. As a result of these advantages, there is a strong economic and environmental argument for replacing all of your older energy-saving bulbs before they expire.

Ricky - This is looks like a no-brainer! Not only are LEDs cheaper in the long run, but they’re better for the environment too. Time to go throw all my old CFLs away!

Andy - CFL bulbs contain environmentally-hazardous mercury and other materials which can be recycled, so when they are swapped out they must only be disposed of in the special facilities available at most recycling centres.


Thanks for the question and answer, I've thought about similar:

We've a 10 year old Plasma 50" TV, brilliant picture still but it's like a mini greenhouse, I could fry an egg on it lol. Cost £900 which is why we haven't binned it but wondering how much extra it's costing us over a £300 LED TV same size we could now purchase.

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